1. Field of the Invention
The present invention relates to a carbon fiber reinforced carbon having high strength, excellent heat resistance, abrasion resistance and anti-oxidation resistance. The carbon fiber reinforced carbon is suitable to a sliding material for making a brake shoe and a brake lining of an aircraft and a racing car, and a bearing for a high temperature application.
2. Description of the Prior Art
A sliding member utilized for an aircraft, a racing car and the like especially requires heat resistance and abrasion resistance. Recently, carbon fiber reinforced carbon has been provided therefor. This carbon fiber reinforced carbon is produced by impregnating a liquid carbonaceaous material (a binder), such as tar, pitch and thermosetting resin into carbon fiber (a reinforcement) which has been carbonized or graphitized and oxidized beforehand. Then, the resulting binder impregnated carbon fiber is sintered in an inert atmosphere. If necessary, the resulting sintered product is graphitized thereafter (Japanese Unexamined Patent Publication No. 206351/1988).
Since the carbon fiber reinforced carbon thus produced uses the liquid carbonaceous material as a binder, volatile substances are generated by the decomposition of the liquid carbonaceous material during the sintering, thereby forming pores. Accordingly, the boundary adhesion between the reinforcement and the binder deteriorates, and the density of the product decreases. The product is accordingly inferior in the strength and the abrasion resistance. Moreover, when a product of a large size is made of the carbon fiber reinforced carbon, such a product lacks homogeneity.
To solve these problems, the pores of the product are filled with a liquid impregnant as a binder, and the product is sintered again to decrease the porosity. But, in spite of these complicated processes, the product is still porous. In addition, these complicated processes have resulted in the increasing manufacturing cost.
Further, a CVD (chemical vapor deposition) method is proposed to solve these problems. In the CVD method, a hydrocarbon gas is decomposed in a high temperature oven and decomposed products are deposited on the surface of the carbon fiber. However, since a uniform thermal decomposition should be done for a long period of time in this method under the condition that no soot should be generated, a sophisticated technique is required to control the condition. Accordingly, the CVD method cannot be done practically.